Blanking clearance and grain size effects on micro deformation behavior and fracture in micro-blanking of brass foil

When the feature dimension of metal forming parts is scaled down to micro-scale, size effects occur and the understanding of micro-forming becomes complex. In this paper, the size effect on deformation behavior of brass foil was investigated via micro-blanking test. The results show that the ultimate shearing strength increases with the decrease of the foil thickness and the fracture mechanism of micro-blanking significantly changes from fracture mode with ductile dimples. There exists a minimum peak value during micro-blanking of brass foil over the considered relative blanking clearance range. However, the deformation behavior of micro-blanking process not only relates with the blanking clearance, but also relates with the grain size of brass foil. The grain size has a significant influence on micro-blanking and the curves of coarse-grained foil specimen show a strong variation not only in the curve profile but also in blanking edge distribution. To explain the size effect mechanism of micro-blanking, a size effect model of micro-blanking was established by considering the blanking clearance and grain size and the results indicate that the ratio of blanking clearance to grain size is one of the main factors to affect micro deformation behavior in micro-blanking. The ultimate shearing strength reaches an extreme value when the blanking clearance to grain size ratio is equal to 1.

► The deformation behavior of micro-blanking relates with both blanking clearance and grain size.
► Fracture mechanism of micro-blanking is changed with the decrease of foil thickness.
► Clearance to grain size ratio is one of the main factors to influence micro-blanking deformation.
► A novel size effect mode is established by considering the blanking clearance and grain size.